With regards to what people were saying during the match with Becker about Andy seeming to lose focus and drifting mentally etc and why the other 3 members of the big 4 don't do it as often (although recently they seem to be doing it much more than usual) I believe it's a crowd thing. Having just watched the replay, the crowd were a very quiet for a majority of it, maybe due to the lacklustre spectacle that it was, maybe not.
But yeah, i always think Andy is like Connors, he feeds of the crowds energy and stays focused more when the crowd are into it, if it's too quiet then he has to generate his own enthusiasm which he probably is getting better at doing but not quite there yet. A prime example of this was the USopen final last year in the final set when he was shouting CMON at the crowd or the match against Baghdatis at Wimbeldon also last year, this is perhaps why the slams are where he plays his best because the crowd are more lively and stadiums are more full, especially the USO.
Just my take on it, probably wrong but meh.
Judging by some of the matches I watched on youtube of Connors, I can say that he
would engage the crowd rather than the other way around. The enthusiasm would come within. He knew what worked for him. Plus, North Americans are very different people. They are open, laid back, very engaging, love to have fun and rarely critical. And very, very supportive of their own players and they don't mind supporting other players as well. In short, they don't hold back. Brits are far more reserved and can be very critical. Anything outside the norm, they are typically appalled. I've seen the same differences between this forum and other forums as well, where majority of the fans are either North Americans or International fans, whereas 99% of this forum members are Brits. And Andy is a British player and as much as he loves to have a very engaging crowd, he's made of the same mold as well. So it's a tough task for Andy to engage the crowd either at Wimbledon or Queens when both are reserved by nature/culture. He'll be far more successful elsewhere, as you mentioned, the USO or Australian or even RG where people love to have fun openly and aren't afraid to show their emotion - good or bad - at least you get an engaged crowd.
Having said that, I'd rather Andy engages the crowd rather than wait for the crowd get engaged. That works far better and should be the way as well. A good display of game, some pumped up attitude and complete focus should really do the job. He can change things around if he really wants it.